Tworzydlo, J. and Tajic, A. and Schomerus, H. and Brouwer, P. W. and Beenakker, C. W. J. (2004) Exponential sensitivity to dephasing of electrical conduction through a quantum dot. Physical Review Letters, 93. p. 186806.
According to random-matrix theory, interference effects in the conductance of a ballistic chaotic quantum dot should vanish propto(tau_phi/tau_D)^p when the dephasing time tau_phi becomes small compared to the mean dwell time tau_D. Aleiner and Larkin have predicted that the power law crosses over to an exponential suppression exp(â��tau_E/tau_phi) when tau_phi drops below the Ehrenfest time tau_E. We report the first observation of this crossover in a computer simulation of universal conductance fluctuations. Their theory also predicts an exponential suppression propto exp(â��tau_E/tau_D) in the absence of dephasingâ��which is not observed. We show that the effective random-matrix theory proposed previously for quantum dots without dephasing explains both observations.
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